Overhead camshaft engine valve mechanism



July 9, 1963 c. H. BOUVY ETAL 3,096,750

OVERHEAD CAMSHAFT ENGINE VALVE MECHANISM Filed July 14, 1961 2Sheets-Sheet 2 INVENTOR5.

United States Patent This invention relates to overhead camshaft enginevalve operating mechanisms and in particular to simplified valve trainconstruction wherein rocker shafts are eliminated and a system of simpleinexpensive valve train elements are employed between conventionalcamshaft lobes and each engine valve stem.

In the particular engine shown in the drawings for the purpose ofillustrating the invention, the camshaft is located in the upper portionof a two part die-cast cylinder head between the intake and exhaustvalve stems which have their axes extending in a V arrangement. Theintake valve stem is located at one side of the longitudinal axis of thecamshaft, and the exhaust valve stem is located on the opposite sidethereof. In the instant invention, a rocker arm actuated by a cam on thecamshaft is fulcrumed about a rocker arm link which is anchored at itslower end by a ball and socket connection to the cylinder head. Theupper end of the said rocker arm link extends through the rocker armwhich is secured by a ball and socket connection to the said rocker armlink. Thus, the rocker arm is mounted on a rocker arm link which is ineffect a self-aligning tension member, thus eliminating the use of arocker arm shaft. The V-arrangement of the valves, which may be offsetin the direction of the longitudinal axis of the camshaft, permits theuse of larger valves resulting in less restricted valve porting. Thismeans that a higher power output can be obtained per unit of pistonarea.

The primary object of the instant invention is to provide an improvedand simplified valve operating mechanism of the type aforesaid which isnot only inexpensive to manufacture and readily installed but is highlyefiicient and is substantially impossible to bind or freeze inoperation, and which, when engine servicing is required, the valveoperating mechanism can be serviced with a minimum of labor cost.

Another object of the invention is to provide a valve stem guide mountedin the cylinder head of an internal combustion engine having formedintegral with the upper end thereof a guide cup for receiving the valvespring disposed between the inner annular base of the guide cup and theouter end of the engine valve stem, the said guide cup serving as aguiding support for a thrust cup telescoped thereover which engages thebifurcated end of the rocker arm and causes the cam end thereof tofollow a cam lobe on the engine camshaft.

A further object of the invention is to provide resilient compressionmeans located between the outer end of the valve stem and the valvecontacting portion of the thrust cup whereby to localize all clearancesin the valve train mechanism at'the top of the valve stem and constantlymaintain all elements of the valve train mechanism in contact, thusstabilizing the valve train mechanism.

Other objects of the invention will become apparent by reference to thefollowing detailed description taken in connection with the accompanyingdnawings, in which:

FIG. 1 is a transverse vertical sectional view through the upper portionof one cylinder of an overhead camshaft internal combustion engineshowing valve operating mechanism embodying the invention, the intakeand exhaust valves being somewhat longitudinally offset.

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FIG. 2 is a top plan view of a rocker ann stamping preferably employed.

FIG. 3 is an end elevational view of the bifurcated thrust cupengagement end of the rocker arm taken on the line 3--3 of FIG. 2.

FIG. 4 is a transverse sectional view of the centnal socket portion ofthe rocker ar-m taken on the line 44 of FIG. 2.

FIG. 5 is a transverse sectional view of the cam contact arm end of therocker arm taken on the line 55 of FIG. 2 showing the hardened camfollower pad preferably employed.

FIG. 6 is a bottom view of the thrust cup which is reciprooatinglymounted on the valve stem guide cup preferably formed integral with thevalve stem guide.

FIG. 7 is a vertical sectional view taken on the line 7-7 of FIG. 6showing the seats provided for the bifurcated end of the rocker arm.

FIG. 8 is a transverse sectional view taken on the line 8-8 of FIG. 7.

Referring now to the drawings wherein like reference characters refer tolike and corresponding parts throughout the several views, the inventionis illustrated in connection with a single cylinder of a multiplecylinder engine.

The single engine cylinder 1%} is provided with a usual piston 11 and awater cooling jacket 12 which, in the illustrated construction, may beformed of a stamping. The connecting rod, crankshaft and crankcase arenot shown since they may be of any suitable design and are well known inthe engine art.

The cylinder head generally designated by the reference character C ispreferably die-cast of aluminum, and is formed of :a lower cylinder headsection 13 and an upper cylinder head section 14'. An exhaust manifold15 is secured in any suitable manner to the lower cylinder head section13 and communicates with an exhaust passage 16 therein leading to anexhaust port 17. An intake manifold 18 is die-east in the lower andupper cylinder head sections 13 and 14 and communicates with an intakepassage 19 in the lower cylinder head section 13 leading to an intakeport 20. The said exhaust and intake ports 17 and 2t communicate with acombustion chamber 21, formed in the lower cylinder head section 13directly above the cylinder 10.

Aligned holes 22 and 23 and aligned holes 24 and 25 are provided in theupper and lower head sections 14 and 13 respectively to accommodate thestems 28d and 295 of exhaust and intake valves 28 and 29 respectively.These pairs of aligned holes 22 and 23 and 24 and 25 have their axes ondiagonal lines converging in a V-formation inwardly toward the verticalaxis of the cylinder 10. A valve stem guide 26 is pressed or otherwisesecured in each of the pairs of aligned holes 22 and 23 and 24 and 25 toreciprocatingly accommodate the valve stems 280 and 29d of the exhaustand intake valves 28 and 29 respectively. The exhaust and intake valves28 and 29 are of the poppet type and have heads 231 and 291 respectivelywhich seat in valve seats 1'71 and 2th) of the exhaust and intake ports17 and 2d respectively.

The valve openating mechanism *or valve train for the exhaust valve 28and intake valve 29 is the same, and is preferably operated from asingle camshaft 32 located on the longitudinal axis of the row of enginecylinders 10 of a multiple cylinder engine and transversely between theexhaust and intake valve stems thereof. The said camshaft 32 hassuitably located and oriented cam lobe 33 thereon, one for each of theexhaust and intake valves 28 and 29 of each cylinder 10. The cam shaft32 is notat'ably mounted on bearings 34 which are suitably supported o-nlongitudinally spaced webs preferably cast integral with the upper headsection 14 of the cylinder 3 head C. The said camshaft 32 is driven intimed relationship to the rotation of the engine crankshaft byconventional means, not shown.

Inasmuch as the valve operating mechanism or valve train for each of theexhaust valve 23 and the intake valve 29 is the same, the said valveoperating mechanism will be described in detail for the exhaust valve28. The valve operating mechanism for each of the exhaust valve 28 andthe intake valve 29 is preferably operated by a separate cam lobe 33 onthe camshaft 32. The cam lobe for operating the intake valve 29 is notshown; however, it is obvious that it is oriented to open the saidintake valve 29 at the proper time in relationship to the engineoperating cycle.

The valve operating mechanism of the invention consists broadly of avalve stem guide 26 including a cup shaped thrust cap guide 260preferably formed integral and concentric on the upper or extending endof the said valve stem guide 26. A thrust cap 36 in the form of aninverted cup is recipnocatingly mounted over the open end of the thrustcap guide 260. The closed end of the said thrust cap 36 is adapted forpressure contact with the upper end of the valve stem 280 of the exhaustvalve 23. A valve compression spring 38 is disposed around the valvestem 280 of the exhaust valve 28 and has its lower end seated in thebottom of the cup shaped thrust \cap guide 260 of the valve stem guide26. The upper end of the said valve compression spring is disposed inabutment against a valve spring retaining cap 39 fixed on the upper endof the valve stem 23 by such means as a two-part retaining ring 46having an inwardly extending flange 41 disposed in a circumferentialgroove 42 formed in the upper end of the valve stem 286. The outerperiphery of the said two-part retaining ring 40 is tapered to fit intothe complementarily inwardly tapered inner periphery of the retainer cap39 which telescopes over the said retaining ring 40.

A rocker arm 43 shown in detail in FIGS. 2-5 inclusive is mounted inball and socket relationship on the upper end of a rocker arm link 44which is also secured in ball and socket relationship to the uppercylinder head section 14. The said rocker arm 43 extends between a camlobe 33 on the camshaft 32 and the thrust cap 36 for imparting valveopening movement to the exhaust valve 28 through its valve stem 280.

To secure the rocker arm link 44 in ball and socket relationship to theupper cylinder head section 14, a threaded bore 45 is formed in the topof the said upper cylinder head section 14 to accommodate a sphericallyshouldered head 44% provided at the lower end of the said rocker armlink 44. A cylindrical retaining bushing 47 having a semi-sphericallower end face 470 is telescoped over the rocker arm link 44 and isthreaded into the said threaded bore 45; the said spherically shoulderedhead 440 on the rocker arm link 44 and the semi-spherical end face 470of the cylindrical retaining bushing 47 being in mating relationshipwhereby to form a ball and socket or universal anchorage of the saidrocker arm link 44 to the top of the upper cylinder head section 14. Thesaid cylindrical retaining bushing 47 has a clearance 54 around therocker arm link 44 so that the said rocker arm link 44 may be free for alimited swivel movement.

The ball and socket connection employed at the upper end of the rockerarm link 44 is accomplished by threading the upper end thereof at 441for receiving a ball end member 50 having a semi-spherical lower face 51which is in contact engagement with a complementarily formedsemi-spherical face 52 stamped in the central portion of the rocker arm43 which forms a lobe 53 in the bottom portion thereof. The said lobe 53of the rocker arm 43 is provided with an elongated aperture 55 thereinto accommodate the rocker arm link 44 and to permit relative movement ofthe rocker arm link 44 with respect to the rocker arm 43 at the matingsemi-spherical faces 51 and 52 of the ball end member 50 threaded on therocker arm link 44 and the rocker arm 43 respectively. A screw driverslot 56 is provided in the upper or outer end of the rocker arm link 44to permit turning of the said rocker arm link relative to the threadedball end member 50 whereby to adjust the clearances normally provided inthe valve train between the cam lobe 33, the rocker arm 43, the thrustcap 36, and the intake valve stem 28% Referring now particularly to therocker arm 43, it is preferably stamped to a generally channel shapedformation, and has its cam contact end provided with a hardened shoe 57having a suitably curved contact surface 58 for contact with the camlobe 33 mounted on the camshaft 32. The said cam contact surface 58 ofthe shoe 57 is preferably crowned as at 59 so as to smoothly follow thesaid cam lobe 33. At the end of the rocker arm 43 opposite the camcontact end thereof, two side walls 60 of the said rocker arm 43 extendoutwardly beyond the base portion '61 thereof and terminate in laterallyspaced arms 62 forming a bifurcated end which straddles the thrust cap36. The two arms 62 of the rocker arm 43 have curved lower ends 63 whichcontact laterally extending diametrically opposite flanges 64 formed atthe lower end or open end of the said thrust cap 36. The flanges 64 ofthe said thrust cap 36 are each provided with a depressed portion 65 toaccommodate the lower curved ends 63 of the two laterally spaced arms 62forming the bifurcated thrust cap contacting end of the rocker arm 43.

The outer periphery of the thrust cap 36 is formed with a flat wall at67 adjacent the curved depressions 65 in the flange 64 to provide slightlateral clearance at the downwardly extending lower curved ends 63 ofthe laterally spaced arms 62 at the bifurcated thrust cap contact ingend of the rocker arm 43. The thrust cap 36 is provided with suitableapertures 68 in the closed end 37 thereof to permit breathing when thethrust cap 36 reciprocates on the guide cup 35.

A leaf type annular compression spring 69 is provided between the valvestem retaining cap 39 and the closed upper end 37 of the thrust cap 36for taking up normal back lash in the valve train between the cam lobe33 and the upper end of the exhaust valve stem 28.

The thrust cap guide 260 formed integral with the valve guide 26provides a rigid bearing over which the thrust cap 36 reciprocates, thuseliminating side thrust on the engine valve stem 280. By the instantinvention, it is possible to eliminate the usual rocker arm shaft andpush rod construction, and a single camshaft may be employed with camlobes thereon to operate the intake and exhaust valves having their axesdisposed in a V-relationship at each engine cylinder. The elimination ofthe rocker arm shaft and the V-arrangement of the intake and exhaustvalves with the camshaft therebetween reduces the overall height of theengine, and eliminates much costboth in original manufacture of theengine and in the servicing thereof.

Inasmuch as the rocker arm- 43 is tension-ally supported on the uppercylinder head section 14 by a rocker arm link 44 having a universalmovement at both the cylinder head section 14 and at the rocker arm 43,a self-aligning tensionally supported valve train mechanism is providedwhich permits cam shaft and earn actuated "and controlled movement ofthe rocker arm 43 and engine valve 28 against the force of a valvecompression spring 38 constantly urging of the engine valve 28 towardits closed position, all Without the use of a rocker shaft and withoutside thrust binding of the valve stem 28%) of the valve 28 in its valvestem guide 26.

As hereinbefore indicated, the valve train construction for the engineintake valve 29 is preferably like and similar to the valve describedfor the engine exhaust valve, the exhaust and intake valves 28 and 29each being operated by a separate cam 33 on the camshaft 32. It isobvious that other cam arrangements may be employed with the instantinvention. Also, the use of a suitable auxiliary spring means 69 withinthe thrust cap 36 acting between the closed end 37 of the thrust cap 36and the upper end of the valve stem 28 functions ably as an antibacklashdevice for each valve train.

Although there are many advantages in employing the invention inconnection with engines having a V-valve aruangement, it is of coursecontemplated that other valve dispositions may be used; for example, anin-line valve arrangement.

Axlthough but a single embodiment of the invention has been disclosedand described in detail, it is obvious that many changes may be made inthe size, shape, arrangement and detail of the various elements of theinvention, all without departing from the spirit and scope thereof asdefined by the appended claims.

We claim:

1. In an internal combustion engine having a cylinder head, intake andexhaust valves arranged in said head, said valves including valve stems,a valve stem guide for each said valve stem including an integral thrustcap guide cup forming an extension of said valve stem guide, a thrustcup for contact engagement with the outer end of said valve stemreciprocatingly mounted on said thrust cap cup, a compression springdisposed in said thrust cap guide cup and in compressive engagement withthe upper portion of said valve stem norm-ally urging said valve toclose, a camshaft disposed between said valve stem guides, a rocker armhaving contact engagement with said camshaft and said thrust cap, and alink anchoring said rocker arm to said cylinder head including meansconnecting said link to said cylinder head permitting limited universalmovement of said link with respect to said cylinder head and meansconnecting said rocker arm to said link permitting a rocking movement ofsaid rocker arm with respect to said link.

2. In an internal combustion engine having a cylinder head, a singleoverhead camshaft, intake and exhaust valves in said cylinder head eachincluding a valve stem extending from said cylinder head arranged withtheir axes on diagonal lines in a V-formation, the intake valves and theexhaust valves being located at opposite sides of the longitudinal axisof said camshaft, compression spring means constantly urging said valvesto their closed position, rocker arms arranged in operative relationshipbetween said camshaft and each said valve stem, means anchoring saidrocker arm to said cylinder head arranged for limited universal movementat said cylinder head and said rocker arm, and resilient clearancetake-up means disposed between said rocker arms and said valve stems.

3. In an internal combustion engine of the overhead camshaft type havinga cylinder head, intake and exhaust valves in said cylinder head, valvestems for said valves, valve stem guides extending through said cylinderhead each having integral guide cups on the upper end thereof, a valvespring disposed in each said guide cup adapted to engage the upperportion of said valve stems for closing said valves, an inverted thrustcut guided for reciprocal movement on each said guide cup, said thrustcaps having contact engagement with the outer ends of said valve stems,a camshaft having its longitudinal axis located alongside said intakeand exhaust valve stems, cams on said camshaft, a rocker arm operativelycontacting each said cam and a thrust cap, and a universal movementtension link betwen each rocker arm and said cylinder head, said tensionlink having a ball and socket connection to said rocker arm and a balland socket connection to said cylinder head, and means limiting theuniversal movement of said tension link.

4. In an internal combustion engine, a cylinder, a cylinder head forminga combustion chamber with said cylinder, a piston reciprocable in saidcylinder, intake and exhaust ports in said cylinder head leading to andfrom said combustion chamber, intake and exhaust valves for opening andclosing said ports including valve stems arranged in V-formationextending through said cylinder head, a camshaft located between saidintake valve stems and said exhaust valve stems, and cam means on saidcamshaft formed to open said valves in a selected timed relationship, avalve stem guide around each said valve stem extending through the saidcylinder head including a cupped thrust cap guide on the outer endthereof, a thrust cap reciprocatingly mounted on each said thrust capguide, a rocker arm opening each valve responsive to said cam meansincluding a cam follower at one end thereof and a bifurcated thrust capengagement formation on the other end thereof engaging said thrust cap,a rocker arm link connected to the cylinder head and to each rocker armwith limited universal movement therebetween, and compression springmeans disposed in each cupped thrust cap guide acting on each valve stemto urge each said valve to close and cause said rocker arm to followsaid cam means, and compression spring means in each said thrust capdisposed between each said valve stem and each said thrust ca-p wherebyto localize clearances in the valve operating mechanism between eachvalve stem and the camshaft and stabilize the rocker arm mechanism.

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1. IN AN INTERNAL COMBUSTION ENGINE HAVING A CYLINDER HEAD, INTAKE ANDEXHAUST VALVES ARRANGED IN SAID HEAD, SAID VALVES INCLUDING VALVESSTEMS, A VALVE STEMS, GUIDE FOR EACH SAID VALVE STEM INCLUDING ANINTERGAL THRUST CAP GUIDE CUP FORMING AN EXTENSION OF SAID VALVE STEMGUIDE, A THRUST CUP FOR CONTACT ENGAGEMENT WITH THE OUTER END OF SAIDVALVE STEM RECIPROCATINGLY MOUNTED ON SAID THRUST CAP CUP, A COMPRESSIONSPRING IN SAID THRUST CAP GUIDE AND IN COMPRESSIVE ENGAGEMENT WITH THEUPPER PORTION OF SAID VALVE STEM NORMALLY URGINGS SAID VALVE TO CLOSE, ACAMSHAFT DISPOSED BETWEEN SAID VALVE STEM GUIDE, A ROCKER ARM HAVINGCONSTANT ENGAGEMENT WITH SAID CAMSHAFT AND SAID THRUST CAP, AND A LINKANCHORING SAID ROCKER ARM TO SAID CYLINDER HEAD INCLUDING MEANSCONNECTING SAID LINK TO SAID CYLINDER HEAD PERMITTING LIMITED UNIVERSALMOVEMENT OF SAID LINK WITH RESPECT TO SAID CYLINDER HEAD AND MEANSCONNECTING SAID ROCKER ARM TO SAID LINK PERMITTING A ROCKING MOVEMENT OFSAID ROCKER ARM WITH RESPECT TO SAID LINK.